Sealing device



Feb. I3,' 1934. A, L, McHUGH 1,947,017

SEALING DEVICE Filed Dec. 22, 1932 IN V EN TOR.

H15 ATTORNEYI Patented Feb. 13, 1934 SEALING DEVICE Anthony L. McHugli, Easton, Pa., assignor to Ingersoll-Rand Company, Jersey City,.N. J., a corporation of New Jersey Application December 22, 1932 Serial No. 648,377

Claims.

This invention relates to scaling devices, and more particularly to a sealing device applicable to pumps and similar machines having shafts extending through an exterior wall of the pump I casing.

One object of the invention is to maintain an effective seal at all times between the pump shaft and the wall of the bore in the pump casing through which the shaft extends.

Another object is to avoid undue wear of the sealing member or members.

Other objects will be in part obvious and in part pointed out hereinafter.

The accompanying drawing is a longitudinal sectional elevation of a pump having the sealing device applied thereto.

Referring more particularly to the drawing, A designates in general a pump comprising a casing B having a pumping chamber C and, in an outer wall, a sealing chamber D which is connected with the pumping chamber by a bore E.

A closure is provided for the outer end of the sealing chamber D by a cover F which may be secured to the casing B in any well known manner. In the cover F is a bore G to accommodate the pump shaft H which also extends through the sealing chamber D and the bore E into the pumping chamber and carries near its free end an impeller J whereby liquid is pumped from an inlet chamber K to a discharge chamber L of the pump.

The portion of the shaft H whereon the impeller J is arranged is preferably of reduced diameter, thus providing a shoulder 0 against located within the sealing chamber D and rotatable with the shaft for maintaining an annulus of sealing liquid in the outer portion of the sealing chamber D during the normal operation of the pump. Interposed between the impellers P and J is a spacer Q, in the form of a sleeve, and a nut R is threaded on the free end of the shaft and acts against the hub of the impeller J to hold the elements mounted upon the reduced portion of the shaft H against 1ongitudinal movement.

The sealing liquid, designated herein by S, may be of the same substance as that being pumped by the impeller J and is of suflicient quantity so that, during the normal operation of the pump, it will be maintained in the outer portion of the sealing chamber D in the form of an annulus of sufficient depth to overlap the outer portion of the impeller P. I

In accordance with the practice .of the inwhich seats an end of a hub of an impeller P vention, means are provided for preventing leakage of liquid through the bore G to-the exterior of the pump during the idle periods of the pump and such periods of operation during which the pump speed is insufilcient to enable the impeller 00 P to maintain the sealing liquid insealing position around the outer extremity of the impeller P. The means provided for this purpose comprises a packing member T arranged in a carrier U disposed about the shaft H and said packing 05 member T is adapted to seat against the outer face of the cover F and encircles the outer extremity of the bore G.

The carrier U, which may be in the form of ,a sleeve, has a groove V in its periphery to receive a collar W having trurmions X which are engaged by the forked ends Y of a yoke Z. The carrier U is interlockingly connected with the shaft H by means of a key 12 which engages a key slot 0 in the carrier of such length that the [5 carrier may slide to and fro upon the shaft H. In the inner surface of the carrier U is a groove d wherein is arranged a packing ring e which bears against the periphery of the shaft H to effect a seal between the shaft and'the carrier.

In the form of the construction illustrated the yoke Z constitutes an integral portion of a rocker arm 1 which is pivotally mounted, upon a pin 9, at a point intermediate its length. The pin g may be supported in any suitable manner as, for example, by a distance piece h interposed between the pump casing and a motor 7' whereby the shaft H is driven.

The distance piece h may also act as a support 7 for a cylinder is containing a reciprocatory pis- 90 ton 0 which is connected to the lower end of the rocker arm 1 by meansof a piston rod p and a pivot pin q extending through the ends of the rocker arm I and the rod p. One end of the piston o constitutes an actuating surface r against which pressure fluid may act to oscillate the rocker arm I and thus actuate the carrier and the packing T out of contact with the cover F. The pressure fluid employed for this purpose preferably consists of a portion of the discharge fluid of the pump, and such fluid is conveyed from the discharge chamber L by a passage 3 in the casing B and a conduit t leading from the passage s to the cylinder 70.

Aflixed to the shaft H is a collar u which acts as a seat for one end of a spring 11 disposed about the shaft H. The opposite end of the spring 1) acts against the collar W to actuate the carrier U in the direction of the pump and thus press the the cover F.

sage K ,to the discharge chamber L. With the shaft H thus operating the impeller P forces the sealing liquid S into the outer portion of the sealing chamber D and retains it there in the form of a rotating annulus which overlaps the outer portion of the impeller P and seals the bore E from the bore G. In other words, the sealing liquid prevents either the flow of liquid from the pump to its exterior, along the shaft H, as well as the entrance of air from the exterior to the pumping chamber.

During this mode of operation of the pump the annulus of sealing liquid in the chamber D will sufilce as a seal about the shaft H and, when thus operating, discharge liquid under pressure flows from the chamber L through the passage s and the conduit t into the cylinder is. There the liquid acts against the actuating surface 1 and moves the piston to rock the arm f about its pivot 9, thus moving the carrier U away from the pump casing a sufficient distance to prevent contact between the packing member T and the cover F.

The carrier U being keyed to the shaft H will rotate therewith but, inasmuch as the packing member T will then be held in non-contacting relation with the cover F, the said packing member T will not be subjected to unnecessary wear,

as would be the case were it permitted to remain in constant contact with the surface wherewith it cooperates to effect a seal.

When the pump is again brought to rest so that, in consequence, the pressure of the liquid within the cylinder 7c decreases to a lower value than that exerted by the spring v the said spring 1; will actuate the carrier U towards the pump and will press the packing member T into sealing relationship with the cover F.

I claim:

1. A sealing device for a pump casing having a bore, a shaft in the bore, a packing device cooperating with the casing to seal the bore and being rotatable with and slidable upon the shaft, pressure fluid actuated means for maintaining the sealing device out of contact with the casing during the operative period of the pump, and means for actuating the sealing device into sealing relationship with the casing during the idle period of the pump.

2. A sealing device for a pump casing having a bore, a shaft in the bore, a carrier rotatable with and slidable upon the shaft, a packing member in the carrier cooperating with the casing to seal the bore, means actuated by the discharge pressure of the pump and acting upon the carrier to maintain the packing member out of contact with the casing during the normal operation of the pump, and a spring opposing the said means to press the packing member into sealing relationship with the casing during the idle periods of the pump.

3. A sealing device for a pump casing having a bore, a shaft in the bore, a carrier rotatable with and slidable upon the shaft, a packing member in the carrier cooperating with the casing to seal the bore, a cylinder, a'piston in the cylinder and being connected to the carrier, a conduit conveying discharge fluid from the. ump to the cylinder to actuate the piston and the carrier for moving and maintaining the packing member out of contact with the casing during the normal operation of the pump, and a spring opposing the said means to press the packing member into sealing relationship with the casing during the idle periods of the pump.

4. In a centrifugal pump, the combination of a casing having a bore and a sealing chamber and a shaft rotatable in the bore and the chamber, sealing liquid in the chamber, means in the chamber rotatable with the shaft to maintain an annulus of sealing liquid in the outer portion of the chamber during the normal operation of the pump, a carrier keyed to the shaft and being slidable thereon, a packing member in the carrier cooperating with the casing to seal the bore, and means actuated by the discharge pressure of the pump and acting upon the carrier to maintain the packing member out of contact with the casing during the normal operation of the pump.

5. In a centrifugal pump, the combination of a casing having a bore and a sealing chamber and a shaft rotatable in the bore and the chamber, sealing liquid in the chamber, means in the chamber rotatable with the shaft to maintain an annulus of sealing liquid in the outer portion of the chamber during the normal operation of the pump, a carrier keyed to the shaft and being slidable thereon, a packing member in the carrier cooperating with the casing to seal the bore, a cylinder, a piston in the cylinder and being operatively connected to the carrier, a conduit conveying discharge fluid under pressure from the pump to the cylinder to actuate the piston and the carrier for maintaining the packing member out of contact with the casing during the normal operation of the pump, a spring acting against the carrier to oppose the pressure fluid acting against the piston, and a packing member effecting a seal between the carrier and the shaft.

ANTHONY L. McHUGH. 

